Conventionally, a portable display device, a so-called liquid crystal projector, has been widely used (e.g., Patent Document 1). This display device projects light from a light source onto a screen, and viewers watch video projected on the screen. FIG. 8 is a diagram illustrating an example of a constitution of a conventional display device. In FIG. 8, a light source unit 50 of the display device comprises a lamp 51, optical filters 54a to 54g, a liquid crystal panel 55, a prism 56, and a lens 57. White light outputted from the lamp 51 is branched into red, green, and blue lights by the optical filters 54a to 54g. The red, green, and blue lights transmit through the liquid crystal panel 55, and are multiplexed by the prism 56. The multiplexed light is projected on the screen 58 through the lens 57, and displayed as video.
FIG. 9 shows devices which can be connected to this conventional display device. In FIG. 9, the display device receives a video signal through an RGB terminal, and any device having an output terminal for an RGB signal can be connected to the display device, for example, a personal computer 201 such as a notebook PC, a video game console 202, an optical disc player 203 for various types of DVDs, an optical disk recorder 204 including a VTR-integrated recorder, a camera-integrated VTR 205, a stationary VTR 206, a BS/CS tuner 207, a TV 208, a hard disk recorder 209 including a recorder integrated with various types of optical disc drives, a STB (Set Top Box) for internet broadcasting 210, a STB for CATV 211, a STB for digital terrestrial broadcasting 212, and a STB for BS HDTV broadcasting 213.
Further, the display device may be provided with a D4 input terminal, a DVI-D input terminal, an IEEEE1394 terminal, a component terminal, an S terminal, a video terminal and the like, in accordance with the formats of signals outputted from the devices connected to the display device.
Meanwhile, there has conventionally been proposed a display device using coherent light, such as laser, as a light source instead of the above-mentioned lamp (e.g., Patent Document 2). When the light source is changed from the lamp to the laser, reduction in power consumption, longer operating life of the light source, improvement in color reproducibility, miniaturization of the optical system, and battery activation can be realized.
Patent Document 1: Japanese Published Patent Application No. 2003-215562 (FIG. 1)
Patent Document 2: Japanese Published Patent Application No. Hei. 6-208089